This invention relates to a process for treating the product obtained from the bromination of pentaerythritol to yield a product enriched in monobromopentaerythritol, dibromoneopentyl glycol or tribromoneopentyl alcohol.
Dibromoneopentyl glycol (DBNPG) is a commercial, reactive flame retardant having especially useful qualities in polyester- and polyurethane-based formulations. A commercial process for producing DBNPG is disclosed in U.S. Pat. No. 3,932,541. While this process produces a useful product, the product is generally only about 80+ wt % DBNPG, with the remainder being monobromopentaerythritol (MBP) and tribromoneopentyl alcohol (TBNPA). Such a DBNPG product has been used in some polyurethane-based formulations, but is not preferred for use in unsaturated polyesterbased formulations since the presence of more than a few percent of MBP and TBNPA is believed to cause color problems. Generally, the DBNPG product should contain at least about 95+ wt % DBNPG for the product to be suitable for use in unsaturated polyester formulations.
In view of these different requirements for DBNPG purity, it would be desirable if the lower purity product could be, when needed, upgraded to the higher purity product.
It is, therefore, an object of this invention to provide a process for enhancing the DBNPG purity of a composition which contains DBNPG, MBP and TBNPA. It is also an object of this invention to provide a process for effecting substantial separation of DBNPG, MBP and TBNPA from each other.